Method and apparatus for cleaning and degreasing metal articles



Jan. 27, 1970 G. LEHNERT ET AL 3,491,778

METHOD AND APPARATUS FOR CLEANING AND DEGREASING METAL ARTICLES Filed Jan. 17, 1967 INVENTORS Gunrher Lehnerr BY Walter Gopon ATTORNEY United States Patent 3,491,778 METHOD AND APPARATUS FOR CLEANING AND DEGREASING METAL ARTICLES Gunther Lehnert, Hannover-Buchholz, and Walter Gopon, Kirchdorf, Germany, assignors to Kabelund Metallwerke Gutehotfnungshutte Aktiengesellschaft, Hannover, Germany, a corporation of Germany Filed Jan. 17, 1967, Ser. No. 609,807 Int. Cl. B08b /08 US. Cl. 134-64 9 Claims ABSTRACT OF THE DISCLOSURE Degreasing apparatus which sequentially sprays solvent and solvent vapor against both sides of a moving strip.

This invention relates to method and apparatus for cleaning and degreasing metal articles; and more particularly concerns an improved use of volatile organic solvents for that purpose.

In the fabrication of articles from metal strip and the like, its vital that such metal strip be free from grease or other foreign material which may interfere with fabricating operations such aswelding and the like. Thus, in making longitudinally seam-welded metal tubing, the pores of the metal surface must be entirely free of grease or other contaminants, if the welded seam is to be free of defects.

Normally, steel and copper strip is protected from corrosion by layers of grease. Aluminum strip usually has a surface layer of oily residue, aluminum dust, etc. as an incident to the manufacture thereof. Accordingly, it is common practice to clean and degrease metal strip or sheet before fabrication thereof. Such cleaning operations normally use volatile organic solvents such as trichlorethylene or ethylene perchlorate.

In one known cleaning procedure, the metal strip is drawn through the liquid solvent and then passed through a stripper for removal of the dissolved residue which has not been rinsed away; and finally is drawn through a second bath of liquid solvent; with repetition of this opreation as desired. However, such procedure has been found to be of limited efficiency due to a reduction in cleansing effect by the boundary layer of solvent is set in motion by the strip as it moves through the bath.

In another known cleaning procedure, a vaporized solution of the solvent is brought into contact with a metal article which is kept at room temperature, causing condensation of the solvent which then drips from the article to effect a rinsing of the dissolved residue; the temperature of the article rising to facilitate the cleaning process. Such procedure is effective, providing the article being cleaned remains exposed to the solvent over a time interval sufiicient to reach the elevated temperature. Such time interval may be from 2 to 30 minutes depending on the nature of the article being cleaned. If the heat rise is insufficient, the quality of the cleaning process is impaired and the condensed solvent will not remove the residue at lower temperatures. Such process is not suitable for the cleaning of metal strip.

Accordingly, an object of this invention is to provide an improved process for cleaning and degreasing metal strip or articles by volatile organic solvents which are applied in both liquid and vapor form under pressure to the strip or article being cleaned.

Another object of this invention is to provide improved cleaning procedures for metal strips or the like while the same are moving at relatively high speeds, wherein the solvent is first applied in liquid form under pressure 3,491,778 Patented Jan. 27, 1970 and then in vapor form also under pressure, whereby residues of foreign matter are effectively removed.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

In the drawing, the single figure is a diagrammatic showing of the method and apparatus for cleaning and degreasing metal such strip and the like, embodying the invention.

Essentially, in accordance with the instant invention, metal strip or the like, which is to be cleaned and degreased, is moved continuously at selected speeds, through a compartment which includes guide rollers for directing the strip in a predetermined path, together with pairs of spray nozzles aimed at opposite sides of the moving strip, whereby first liquid solvent is applied and then vaporized solvent is applied, to complete the cleaning operatron.

Further, there is provided means for collecting the liquid and condensed solvent, filtering the same to remove contaminants, distilling means for separating oily residues from the solvent; together with conduit means and associated accessories for passing solvent in liquid and vapor form to the appropriate nozzles. Suitable valves and control means is also provided for making the cleaning operation substantially automatic.

Thus, as shown in the figure, 10 designates apparatus embodying the invention. The same comprises a compartment or tank 11 having a removable cover 12 arranged thereon to provide inlet means 13 and outlet means 14 for passing into and out of said tank 11, a continuously moving metal strip M which is to be cleaned and degreased. A bracket 15 depends from cover 12 toward a lower portion of tank 11 and carries a guide roller 16 at the lower end thereof. A pair of guide rollers 17 in the upper portion of tank 11 cooperate with guide roller 16 to direct the moving strip M from inlet means 13, downwardly and then upwardly and finally out through outlet means 14.

The bracket 15 also carries a pair of horizontally displaced spray nozzles 18, 19 which are aimed at one side of moving strip M. A nozzle 20 is mounted Within tank 11, substantially aligned with nozzle 18 and aimed at the other side of strip M, While a second nozzle 21, also mounted in tank 11 and aligned with nozzle 19, is also aimed at the other side of strip M.

Liquid organic solvent such a trichlorethylene, ethylene perchlorate or the like, is collected in the bottom of tank 11, as at 22. The level of solvent 22 is maintained at a predetermined point by means of a float device 23 which controls a valve 24 in an outlet line 25 of a supplementary tank 26 carrying make-up solvent 27; the line 25 extending into tank 11.

A filter device 28 communicates With tank 11 by way of a transfer passage 29 whereby surface layer portions of collected solvent 22, free from settled residue, passes through said filter device 28 and a magnetic separator 30 for removing metal particles; a fine meshed sieve, as at 30A, is located within the filter device 28. A pump 31 in the outlet of the filter device 28 passes filtered solvent by way of a conduit 32 to spray nozzle 20. Spray nozzle 18 is also connected to conduit 32 by flexible line, not shown; whereby the moving strip M is subjected to sprays of solvent under pressure on both sides thereof. The filter device 28 is located slightly below passageway 29, so that the top surface portion of solvent 22 which is relatively free of settled impurities, passes through the sieve 30A, magnetic separator 30 and the filter means; thus avoiding clogging of the pump 31 and the conduits leading therefrom.

Vaporized solvent for spray nozzles 19, 21 is provided by pump 31 via line 33 and a valve 34 which passes liquid solvent from filter device 28 to a distilling device 35 with a heating element 36 therein for vaporizing the liquid solvent which passes by way of a line 37 and a three-way valve 38 to nozzle 21 and also, to nozzle 19 by way of a flexible conduit, not shown. When no vaporized solvent is to be sprayed, valve 38 is operated to pass such solvent by way of trap 39 to tank 11, in condensed, liquid form.

Float control means 40 regulating valve 34, is operative to maintain a constant level 41 of solvent in distilling device 35. As the liquid solvent is vaporized in device 35, the proportion of oil or grease residue increases. Means is provided for limiting the proportion of such residue in device 35, say 60%. Since the volume of liquid in device 35 is constant, and a constant source of heat 36 is applied to the liquid; the temperature of the liquid mixture is a function of its oil and grease content.

Accordingly, a thermostat control 32 set to operate at a predetermined temperature corresponding to the predetermined oil and grease content of the liquid mixture, is effective to operate a signal device, such as an indicator light or the like, at which time, outlet means 43 is used to draw off a portion of the contents of device 35 and replacing the same with solvent from tank 11 through operation of valve 34.

It will be apparent that the moving strip M is initially subjected to sprays of solvent under pressure from nozzles 18, 20, which are preferably angled downwardly for optimum effect. Any residual foreign matter not removed by spray nozzles 18, 20 is eliminated by the action of vapor spray nozzles 19, 21; which are particularly effective in respect to matter contained in the surface pore structure of strip M.

The draining of oil, grease solvent mixture from device 35 by way of outlet 43 to reduce the proportion of oil and grease in the solvent subject to distillation, may be made automatic by suitable control means, not shown.

- To stabilize the heating of tank 11 caused by the presence of solvent vapor therein, suitable cooling coils 44 are located in the upper portion of the tank 11, whereby the temperature in the tank does not exceed about 60 C. Coils 44 also convert the rising solvent vapor to liquid form which return to the bottom of tank 11. The heat supplied in distilling device 35 by elements 36 is proportioned to the constant volume of liquid therein.

The cover 12 may be moved toward and away from tank 11 by suitable means such by a hydraulic piston or a chain drive; to facilitate the feed of strip M into place over guide rollers 17.

As various changes might be made in the herein disclosed embodiment of the invention without departing from the spirit thereof, it is understood that all matter herein shown or described shall be deemed illustrative and not by way of limitation except as set forth in the appended claims.

What is claimed is:

1. Apparatus for cleaning and degreasing metal tape moving in a given path at relatively high speed comprising guide roller means for directing said moving tape through a pair of successive substantially vertical path portions, solvent collecting tank means beneath said guide roller means, spray means connected to said tank means sides of the tape moving through one of said substantially vertical path portions, means for vaporizing solvent connected to said tank means, and spray means connected to said vaporizing means for spraying vaporized solvent under pressure on opposite sides of the tape moving through the other of said substantially vertical paths.

2. Apparatus as in claim 1, said guide roller means comprising a pair of laterally displaced guide rollers in an upper portion of said tank means, a single guide roller in the lower portion of said tank means and located between said pair of guide rollers.

3. Apparatus as in claim 2 and further including cover means removably mounted on said tank means and providing inlet and outlet means therebetween for said moving tape bracket means on said cover means depending into said tank means, said single guide roller being mounted on said bracket means.

4. Apparatus as in claim 1 and further including filter means arranged to receive top surface portions of the solvent collected in said tank means, and pump means for passing filtered liquid solvent to said first and second conduit means.

5. Apparatus as in claim 4 and further including valve means in said second conduit means and means for controlling said valve means in response to changes in the level of liquid solvent in said vaporizing means.

'6. Apparatus as in claim 1 wherein each spray means is directed downwardly toward said moving tape.

7. Apparatus as in claim 1 and further including supplemental tank means for liquid solvent, conduit means connecting said supplemental tank means with said tank means, valve means in said last mentioned conduit means, and level responsive sensing means in said tank means for controlling said valve means.

8. Apparatus as in claim 1 and further including thermostatic means in said vaporizing means responsive to variations in the composition of the solvent therein for operating signal means.

9. Apparatus as in claim 1 and further including cooling means in the upper portion of said tank means for condensing vaporized solvent.

References Cited UNITED STATES PATENTS 1,521,390 12/1924 Reynolds 134.-15 XR 2,104,102 1/1938 Ruthven 134-15 2,234,593 3/1941 Ferm et al. l3440 XR 2,255,859 9/1941 Quigley 134-31 XR 2,372,599 3/1945 Nachtman 134-15 XR 2,529,762 11/1950 Brisse 13415 XR 2,717,845 9/1955 Carter 134--15 X-R 2,993,493 7/1961 Edhofer 134--31 XR 3,123,083 3/1964 Kearney 134-11 XR 3,144,872 8/1964 Kearney 134-40 XR 3,238,065 3/1966 Fullhart 134-11 MORRIS O. WOLK, Primary Examiner D. G. MILLMAN, Assistant Examiner US. Cl. X.R. 

